The most interesting feature of WordPress which I like is Child Theme. A WordPress child theme is a theme that inherits the functionality of another theme, called the parent theme, and allows you to modify, or add to, the functionality of that parent theme without having to edit the original/parent theme template files. Since the child theme is stored separately, you don’t need to redo the changes next time you upgrade the theme. For this reason, child themes are the recommended way of making modifications to a theme.
Child themes let you start with the basics of an existing theme, so you’re not having to reinvent the wheel. You can pick a theme that has the functionality and basic layout you need, but then customize everything about it as you would designing a theme from scratch. So, choose a good WordPress original/parent theme is very important. I recommend that you choose a WordPress Theme Framework.